The stainless scrubbies, and mothballs. (Either type, para or naphthalene.) The mothballs are an EPA-registered pesticide these days, the concentrated fumes are quite toxic so make Real Damned Sure to hold your breath and open ventilation to air the boat
out before you re-enter it. I wouldn't leave bleach in the bilge
, metal parts
and some plastics degrade after long-term contact with it.
The naphthalene mothballs (harder to get, usually from overseas) have the nice side-effect of mothballing the boat
, they literally prevent rust as they sublimate and coat things with a thin film.
You may also find things like wasp nests in the boom and mast
drains. These are also prevented by inserting bags of mothballs followed by stainless scrubbies.